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Starfish or sea stars are star ... while ophiuroids have clearly demarcated slender arms strengthened by paired fused ossicles forming jointed "vertebrae". [96] The ...
Echinoderms possess a simple digestive system which varies according to the animal's diet. Starfish are mostly carnivorous and have a mouth, oesophagus, two-part stomach, intestine and rectum, with the anus located in the centre of the aboral body surface. With a few exceptions, the members of the order Paxillosida do not possess an anus.
The bilateral body plan most animals have stems from molecular-level genetic actions that can be traced in the head and trunk, or main body, regions, which is why vertebrates, like humans, and ...
Ossicles are small calcareous elements embedded in the dermis of the body wall of echinoderms.They form part of the endoskeleton and provide rigidity and protection. They are found in different forms and arrangements in sea urchins, starfish, brittle stars, sea cucumbers, and crinoids.
Starfish are some of the strangest creatures of the animal kingdom—so much so that scientists didn’t even know for sure if the animals had heads.
Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus 'brittle star'; from Ancient Greek ὄφις (óphis) 'serpent' and οὐρά (ourá) 'tail'; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish.
Marine vertebrates are vertebrates that live in marine environments, which include saltwater fish (including pelagic, coral and deep sea fish) and marine tetrapods ...
Madreporite of Asterias. In sea stars, water enters the system through a sieve-like structure on the upper surface of the animal, called the madreporite.This overlies a small sac, or ampulla, connected to a duct termed the stone canal, which is, as its name implies, commonly lined with calcareous material.